1. Field of the Invention
The present invention relates to an exposure method and exposure apparatus used when producing a semiconductor integrated circuit, a liquid crystal display element, a thin film magnetic head, or another microdevice or a photomask by photolithography and to a density filter used in such an exposure method and exposure apparatus.
2. Description of the Related Art
In photolithography, one step in the production of a microdevice, use is made of an exposure apparatus for projection exposure of images of patterns of a photomask or reticle on to a substrate for exposure (semiconductor wafer or glass plate coated with a photoresist, light-transparent substrate called a xe2x80x9cblankxe2x80x9d, etc.) In recent years, to deal with the increasingly large size of the exposure area accompanying the increased size of substrates, a stitching type exposure apparatus which partitions the exposure area of the substrate into a plurality of unit areas (hereinafter sometimes referred to as xe2x80x9cshotsxe2x80x9d or xe2x80x9cshot areasxe2x80x9d) and successively projects and exposes images of corresponding patterns on the shots has been developed.
In such an exposure apparatus, there was sometimes misalignment in stitched portions of shots due to aberration of the projection optical system, positioning error of the mask or substrate, etc. Therefore, part of the images of patterns for one shot was superposed over part of the images of the patterns for another shot adjoining it for the exposure. At overlay parts of images of patterns, the exposure becomes greater than portions other than overlay parts, so for example the line width (width of lines or spaces) at overlay parts of patterns formed on the substrate become thinner or thicker in accordance with characteristics of the photoresist.
Therefore, the distribution of exposure at the portions forming overlay parts of the shots is set at an incline so as to become smaller the further toward the outside and the exposure of overlay parts is made equal to the exposure of portions other than overlay parts by two exposures in total so as to prevent a change in line width at these overlay parts.
As art for realizing inclined distribution of exposure at overlay parts of shots, it is known to form light-attenuating parts limiting by an incline the amount of light passing through portions corresponding to overlay parts of the reticle itself. Due to the formation of the light-attenuating parts in the reticle itself, however, the steps and cost of the manufacturing process of the reticle increase and the cost of manufacturing the microdevice etc. increase.
Therefore, an exposure apparatus is being developed which is provided with a density filter formed with a light-attenuating part similar to the above on a glass plate at a position substantially conjugate with the pattern formation surface of the reticle or which is provided with a blind mechanism having a light-blocking plate (blind) able to advance into or retract from the optical path at a position substantially conjugate with the pattern formation surface of the reticle and realizes an inclined distribution of exposure by making the light-blocking plate advance or retract during the exposure processing of the substrate.
In the above exposure apparatus of the related art, however, the density filter used for equalizing the exposure of overlay parts and the exposure of portions other than overlay parts is produced as follows. That is, use is made of an exposure sensor provided on the stage carrying the substrate for measuring the exposure and the exposure sensor is made to move in the substrate plane to measure the distribution of exposure near overlay parts. Further, the angle of inclination of the distribution of the amount of transmitted light (that is, the distribution of the transmittance of the light-attenuating part) at the density filter is set so that the exposure of overlay parts becomes equal to the exposure of portions other than overlay parts based on the results of measurement of the exposure apparatus.
If such a designed density filter is used to limit at an incline the exposure of overlay parts when overlaying and exposing parts of images of patterns, if the exposure is performed by the designed exposure, the exposure at overlay parts and the exposure at portions other than overlay parts will match and the line width of patterns formed at overlay parts will become equal to the line width of patterns formed at portions other than overlay parts. When actually trying to expose patterns, however, the width of the lines at overlay parts becomes thinner and the width of the spaces becomes thicker. This phenomenon is believed to arise due to the following reasons:
First, xe2x80x9cflarexe2x80x9d arising due to multiple reflections in the projection optical system provided in the exposure apparatus or multiple reflections between the substrate and projection optical system, between the substrate and reticle, and between the reticle and substrate may be considered. That is, when flare occurs, the effect of flare felt at portions other than overlay parts is constant, but since overlay parts are exposed several times, the effect of the flare is received two or four times and therefore the exposure at overlay parts becomes larger than the exposure of portions other than overlay parts. Therefore, as a result, the exposure of overlay parts becomes larger than the exposure of portions other than overlay parts, so the width of the lines becomes thinner and the width of the spaces becomes thicker.
Second, once exposed, a photoresist coated on a substrate has the characteristic of a higher optical transmittance at the exposed portions. Therefore, if overlay parts are exposed two or four times, the amount of light passing through the photoresist and reflected at the surface of the substrate increases, so as a result a greater exposure is performed than the designed exposure. Accordingly, the exposure of overlay parts becomes larger than the exposure of portions other than overlay parts, so the width of the lines becomes thinner and the width of the spaces becomes thicker.
Third, this phenomenon may be due to error in the design of the density filter. As explained above, a density filter used to make the exposure of overlay parts the same as the exposure at other than overlay parts uses an exposure sensor to measure the distribution of exposure near overlay parts and sets the distribution of exposure at an incline to become smaller toward the outside. This exposure sensor is provided with a photoelectric sensor and a slit plate provided on the light receiving surface of the photoelectric sensor. The exposure is measured by measuring by this photoelectric sensor only the exposure light passing through the slits formed in the slit plate. The slit plate is generally comprised of a quartz substrate on which chrome (Cr) is deposited and then patterned. When using these slits, the exposure light is reflected at the slit plate at the time of measurement of the exposure light and the reflected light is reflected at the projection optical system or the reticle resulting in flare. In general, since the reflectance of the chrome surface is higher than the reflectance of the substrate surface coated with the photoresist in the wavelength region of the exposure light, the amount of flare arising when measuring the spatial distribution of exposure using the exposure sensor becomes larger than the amount of flare arising at the time of actual exposure. Therefore, the exposure sensor measures a greater amount of exposure light than at the time of actual exposure and the density filter is prepared based on the result of measurement. Since the thus prepared density filter is not one which actually equalizes the exposure of overlay parts and the exposure at portions other than overlay parts, it is possible that when using this density filter for exposure, the line width of patterns formed at overlay parts and the line width of patterns formed at portions other than overlay parts become different.
Further, when the line width of the patterns of overlay parts is formed different from the line width of portions other than overlay parts, the practice has been not to change the characteristics of the density filter, but to prepare a reticle adjusting the line width of patterns formed at portions corresponding to overlay parts in patterns formed at the reticle for the exposure. That is, to make the line widths of overlay parts and portions other than overlay parts equal, the practice had been to adjust the line width of the patterns of portions corresponding to overlay parts of the reticle without changing the configuration of the exposure apparatus, including the density filter. With this method, however, it was necessary to select the related parts of patterns from the immense reticle data and finely adjust the line widths at those portions. This work was extremely troublesome. Note that the above explanation assumes that the line widths of patterns to be transferred to the substrate are equal at overlay parts and portions other than overlay parts, but when the line widths of patterns are different, even if the line width matches the design value at one of overlay parts and portions other than overlay parts, the line width of the other will differ from the design value and therefore exactly the same problem will occur as above.
An object of the present invention is to improve the uniformity of line width or pitch of patterns formed on overlay parts where peripheral parts are superposed and portions other than overlay parts when transferring patterns to a plurality of areas where peripheral parts partially overlap on a sensitive object, that is, to make the line width or pitch of patterns substantially match predetermined values at overlay parts and portions other than overlay parts and improve the uniformity or control accuracy of the line width of patterns (transferred images) in individual areas or at the entire surface of the plurality of areas to enable the formation of high accuracy patterns.
Another object of the present invention is to achieve uniform distribution of exposure at individual areas or the entire surface of a plurality of areas when exposing a plurality of areas where peripheral parts are partially superposed on a sensitive object by energy beams or to make the exposures at different points in individual areas or a plurality of areas substantially match corresponding target values so as to improve the control accuracy of exposures at individual areas or the entire surface of a plurality of areas. Still other objects of the present invention will become clear from the following explanation.
According to a first aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising irradiating an energy beam through said setting device set so that the energy at peripheral parts becomes a predetermined first distribution, measuring the distribution of exposure at portions corresponding to the peripheral parts on the sensitive object, and determining a second distribution by which the exposure at the peripheral parts becomes a target amount based on the measured distribution of exposure.
When exposing a plurality of areas where peripheral parts are partially superposed, since the method fires an energy beam by an energy giving a first distribution, measures the distribution of exposure at peripheral parts at that time, and determines a second distribution where the exposure at peripheral parts becomes a target value based on the distribution of exposure obtained by actual measurement, even if there is the effect of flare etc. at the time of exposure, the exposures at overlay parts where the peripheral parts are superposed and portions other than overlay parts can be made substantially equal. Therefore, when transferring patterns with substantially equal line width or pitch at overlay parts and portions other than overlay parts, the uniformity of line width or pitch can be improved between patterns formed at overlay parts and patterns formed at portions other than overlay parts and as a result fine patterns can be formed with good accuracy.
In this case, said first distribution may be set based on a distribution of energy on a predetermined plane at which said sensitive object is arranged, obtained by detecting said energy beam through said setting device, or its integrated value. Further, said first distribution may be set theoretically. Here, xe2x80x9cset theoreticallyxe2x80x9d means set geometrically so as to give a linearly inclined distribution of attenuation. This includes such a geometrically set distribution corrected based on known optical characteristics. For example, there are methods correcting the optical characteristics (distortion, image plane curvature, etc.) of an illumination system firing an energy beam on patterns or error due to occurrence of diffracted light exceeding a numerical aperture (NA) of the illumination system from the attenuating part (comprised of dots etc.) of the density filter of the setting device.
When the first distribution is set based on the distribution of energy in a predetermined plane at which said sensitive object is arranged or its integrated value, when the photodetection device for measuring the distribution of exposure is configured by providing a photodetector at a light-blocking plate, the reflectance of the surface of the light-blocking plate may be made substantially the same as the reflectance of the surface of the sensitive object. Further, the size of the light-blocking plate may be made at least about the same degree as an area irradiated by said energy beam. By doing this, when measuring the distribution of energy or its integrated value, it is possible to eliminate the effect of reflection of the light-blocking plate and measure the distribution of energy or its integrated value in a state close to the state where the sensitive object is actually exposed, so it is possible to make the exposure of overlay parts equal to the exposure at other than overlay parts by a higher accuracy.
Note that the photodetector of the photodetection device in the specification of the application should include at least a light receiving surface. Specifically, for example, when providing the photodetector on the substrate stage for substrate movement, all of the components may be provided on the substrate stage, but it is also possible to provide as little as the light receiving surface among the components of the photodetector on the substrate stage and provide the other parts outside the substrate stage.
Further, when the first distribution is set based on the distribution of energy in a predetermined plane where the sensitive object is arranged or its integrated value, if the photodetection device for measuring the distribution of exposure is configured by providing a photodetector at a light-blocking plate, it is possible to detect the detected value of said photodetector based on a value corresponding to error of the detected value of the photodetector arising due to the difference of the reflectance of the surface of the light-blocking plate from the reflectance of the surface of said sensitive object and/or the difference of the size of the light-blocking plate from the area irradiated by the energy beam so as to find said distribution of exposure. According to this, when finding the distribution of exposure, the value is corrected considering the difference of the reflectance and/or size of the light-blocking plate, so it is possible to make the exposure of overlay parts equal to the exposure at other than overlay parts by a higher accuracy even if it is not possible to make the reflectance or size of the light-blocking plate equal to that of the sensitive object.
The second distribution may be determined considering also the change in optical characteristics due to multiple exposure of peripheral parts. The xe2x80x9cchange in optical characteristicsxe2x80x9d means for example fluctuation of transmittance of the resist on the substrate due to exposure etc. Further, the setting device may include a density filter having an attenuating part attenuating the energy beam limiting the energy at the peripheral parts to said first distribution. In this case, it is possible to adjust the attenuation characteristic of the attenuating part based on the determined second distribution, and expose each of the plurality of areas by the energy beam through the adjusted density filter. The attenuation characteristic is adjusted by for example exchanging density filters, changing the distribution of transmittance by liquid crystal elements etc., reprocessing the density filter, etc.
Further, in the above method of exposure, it is also possible to multiply expose a sensitive object by said energy beam to measure the distribution of exposure. The sensitive object in this case includes a sensitive object the same as or separate from the xe2x80x9csensitive objectxe2x80x9d to which the patterns are transferred. Further, xe2x80x9cmeasure the distribution of exposurexe2x80x9d in this case includes, in addition to measurement of the distribution of exposure due to an illumination uniformity sensor, compensation for error of exposure arising due to fluctuations in transmittance of the resist due to the multiple exposure.
As said setting device, it is possible to use one including a density filter having an attenuating part gradually reducing the energy of the energy beam. In this case, it is possible to change the position of the density filter with respect to a mask on which the patterns to be transferred are formed to change the width of a second overlay part where an image of the attenuating part is superposed based on the determined second distribution without changing a width of a first overlay part where peripheral parts are superposed and thereby adjust the exposure of the first overlay part. The adjustment of the exposure of the first overlay part includes the case of just changing the position of the density filter without switching it and the case of both switching the density filter and changing its position. When adjusting exposure by both switching the density filter and changing the position, it is possible to use a density filter set based on a second distribution where the attenuation characteristic is determined. As one example, it is possible to set the attenuation characteristic of the density filter based on the distribution of exposure obtained by detection of the energy beam by the photodetector and change the position of the density filter to cancel the error of exposure remaining even when using this density filter (for example, arising due to fluctuation of optical characteristics of the resist due to multiple exposure). Further, it is possible to change the distribution of the energy beam limited by said density filter and the relative position with the patterns to be transferred so as to adjust the exposure at overlay parts where peripheral parts are superposed. In this case, it is possible to use patterns obtained by enlarging the patterns to be transferred in the direction of overlay parts (stitching direction). By doing this, it is possible to easily adjust the exposure of overlay parts by just changing the relative positions of the mask and density filter. Further, since only the relative positions of the mask and density filter are changed, no time is required for processing and as a result the throughput can be improved.
Further, when using a setting device including a density filter having an attenuating part gradually reducing the energy of the energy beam, by changing the optical characteristics of an optical system from said density filter to a mask where the patterns to be transferred are formed to change the width of a second overlay part where an image of the attenuating part is superposed based on the determined second distribution without changing a width of a first overlay part where peripheral parts are superposed, it is possible to adjust the exposure of the first overlay part. The adjustment of the exposure of the first overlay part includes the case of just changing the optical characteristics of the optical system without switching the density filter and the case of both switching the density filter and changing the optical characteristics of the optical system. When adjusting the exposure by both switching the density filter and changing the optical characteristics of the optical system, it is possible to use a density filter set based on a second distribution where the attenuation characteristic is determined. As one example, it is possible to set the attenuation characteristic of the density filter based on the distribution of exposure obtained by detection of the energy beam by the photodetector and cancel the error of the exposure remaining even when using this density filter (for example, arising due to fluctuation of the optical characteristics of the resist due to multiple exposure) by changing the position of the density filter.
Further, it is possible to change the optical characteristics (for example, the magnification) of the optical system from the density filter to the patterns to be transferred to change the distribution of the energy beam limited by said density filter and the relative position with the patterns to be transferred so as to adjust the exposure at overlay parts where peripheral parts are superposed. By doing this, it is possible to easily adjust the exposure of overlay parts by just changing the magnification of the optical system. Further, since no time is required for adjusting the optical system (changing the magnification etc.), the throughput can be improved.
Further, in the specification of the present application, the xe2x80x9cimage of the attenuating partxe2x80x9d in the description xe2x80x9cchange the width of a second overlay part where an image of the attenuating part is superposedxe2x80x9d means the image of the attenuating part in the case where there is no light-blocking object (for example, blind, light-blocking band of mask, etc.) interposed in the optical path of the exposure light.
According to a second aspect of the present invention, there is provided a exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising irradiating an energy beam through said setting device and making the reflectance of the surface of a light-blocking plate of a photodetection device having a photodetector and said light-blocking plate used for measuring the distribution of exposure at portions corresponding to peripheral parts on the sensitive object substantially the same as the reflectance of the surface of said sensitive object. In this case, the exposure at the peripheral parts may be set based on said measured distribution of exposure and a change in optical characteristics due to multiple exposure of peripheral parts.
According to a third aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising irradiating an energy beam through said setting device and making a size of a light-blocking plate of a photodetection device having a photodetector and said light-blocking plate used for measuring the distribution of exposure at portions corresponding to peripheral parts on the sensitive object substantially the same as an area irradiated by said energy beam. In this case, the exposure at the peripheral parts may be set based on said measured distribution of exposure and a change in optical characteristics due to multiple exposure of peripheral parts.
According to a fourth aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising irradiating an energy beam through said setting device, detecting said energy beam by a photodetection device having a photodetector and light-blocking plate used for measuring a distribution of exposure at portions corresponding to the peripheral parts on said sensitive object, and setting the exposure at said peripheral parts based on information relating to the difference between the reflectance at said light-blocking plate and the reflectance of said sensitive object and the results of detection. In this case, it is possible to correct the detected value of said photodetector based on said difference of the reflectances to find the distribution of exposure. At this time, preferably the exposure is set considering the change in optical characteristics due to multiple exposure of peripheral parts.
According to a fifth aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising irradiating an energy beam through said setting device, detecting said energy beam by a photodetection device having a photodetector and light-blocking plate used for measuring a distribution of exposure at portions corresponding to the peripheral parts on said sensitive object, and setting the exposure at said peripheral parts based on information relating to the difference between the size of said light-blocking plate and the area irradiated by said energy beam. At this time, preferably the exposure is set considering the change in the optical characteristics due to multiple exposure of peripheral parts.
According to a sixth aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising performing test exposure of a test sensitive object by said energy beam through said setting device set so that the exposure at the peripheral parts has a predetermined first distribution, measuring the shapes of images of patterns of an overlay part, formed on said test sensitive object, where peripheral parts are superposed, determining a second distribution so that the shapes of images of patterns measured become target values, and performing main exposure by setting the setting device to obtain the determined second distribution.
According to a seventh aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising providing said setting device with a density filter having an attenuating part gradually reducing the energy of the energy beam and changing the position of the density filter with respect to the patterns to be transferred to change the width of a second overlay part where the image of the attenuating part is superposed without changing the width of a first overlay part where the peripheral parts are superposed so as to adjust the exposure of said first overlay part. In this case, it is possible to further use patterns obtained by enlarging the patterns to be transferred in the direction of the overlay part. Further, it is possible to set the width of the first overlay part larger than the width of the attenuating part of the density filter.
According to an eighth aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising providing said setting device with a density filter having an attenuating part gradually reducing the energy of the energy beam and changing the distribution of the energy beam limited by the density filter and the relative position with the patterns to be transferred so as to adjust the exposure at an overlay part where the peripheral parts are superposed. In this case, it is possible to use patterns obtained by enlarging the patterns to be transferred in the direction of the overlay parts.
According to a ninth aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising providing said setting device with a density filter having an attenuating part gradually reducing the energy of the energy beam and changing the optical characteristics (for example, the magnification) of an optical system from said density filter to patterns to be transferred to change the width of a second overlay part where an image of said attenuating part is superposed without changing the width of a first overlay part where the peripheral parts are superposed so as to adjust the exposure of said first overlay part.
According to a 10th aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising providing said setting device with a density filter having an attenuating part gradually reducing the energy of the energy beam and changing the optical characteristics of an optical system from said density filter to patterns to be transferred to change the distribution of the energy beam limited by said density filter and the relative position with the patterns to be transferred so as to adjust the exposure at overlay parts where the peripheral parts are superposed.
According to an 11th aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising providing said setting device with a plurality of density filters having different attenuating characteristics of attenuating parts gradually reducing the energy of the energy beam and switching the density filters to adjust the exposure at overlay parts where peripheral parts are superposed.
According to an 12th aspect of the present invention, there is provided an exposure method for transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each of the areas by an energy beam through a setting device gradually reducing exposure at the peripheral parts, comprising setting the exposure of peripheral parts based on a change in optical characteristics due to multiple exposure of peripheral parts.
In the methods of exposure according to the first to 12th aspects of the present invention, it is possible to partition a pattern obtained by enlarging a transfer pattern into a plurality of parent patterns and transfer an image of each of the parent patterns reduced by a projection optical system to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each area by an energy beam through a setting device gradually reducing the exposure at the peripheral parts.
According to an 13th aspect of the present invention, there is provided a photomask produced using the methods of exposure according to the first to 12th aspects of the present invention. Since the exposure of overlay parts is adjusted at a high accuracy, the difference between the patterns formed at overlay parts and the patterns formed at portions other than overlay parts when forming patterns having equal line widths at overlay parts and portions other than overlay parts becomes smaller and it is possible to produce an extremely fine, large area photomask.
According to a 14th aspect of the present invention, there is provided a method of production of a density filter used in an exposure apparatus transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each area by an energy beam through a density filter having an attenuating part gradually reducing the exposure at the peripheral parts, comprising exposing a sensitive object by an energy beam through a test density filter having an attenuating part set so that the exposure at said peripheral parts has a predetermined first distribution, measuring the distribution of exposure at portions corresponding to the peripheral parts on said sensitive object, determining a second distribution where the exposure at the peripheral parts becomes a target value based on the measured distribution of exposure, and forming said attenuating part so as to give said determined second distribution. In this case, the attenuating characteristic of an attenuating part of said density filter may be set by adjusting the distribution of density of light-blocking dots formed on the surface of a transparent substrate forming said density filter.
According to a 15th aspect of the present invention, there is provided a method of production of a density filter used in an exposure apparatus transferring patterns to a plurality of areas where peripheral parts are partially superposed on a sensitive object by exposing each area by an energy beam through a density filter having an attenuating part gradually reducing the exposure at the peripheral parts, comprising exposing a test sensitive object by an energy beam through a density filter having an attenuating part set so that the exposure at said peripheral parts has a predetermined first distribution, measuring the shape of images of patterns of peripheral parts formed on said test sensitive object where said peripheral parts are superposed, determining a second distribution where the measured shapes of the images of the patterns become target values, and forming said attenuating part so as to give said determining second distribution. In this case, the attenuating characteristic of an attenuating part of said density filter may be set by adjusting the distribution of density of light-blocking dots formed on the surface of a transparent substrate forming said density filter.
According to a 16th aspect of the present invention, there is provided an exposure apparatus provided with a density filter produced using the method of production of the density filter according to the 14th aspect or 15th aspect of the present invention.
According to a 17th aspect of the present invention, there is provided a method of production of an exposure apparatus exposing by an energy beam each of a plurality of areas where peripheral parts are partially superposed on a sensitive object, comprising firing said energy beam through a density filter gradually reducing the exposure at peripheral parts, measuring the distribution of exposure at portions corresponding to the peripheral parts on said sensitive object, and preparing a density filter formed with an attenuating part of said energy beam so that the distribution of exposure becomes a target value at said peripheral parts based on the measured distribution of exposure and information relating to the attenuation characteristic of said density filter. In this case, the former density filter (density filter on which energy beam is fired) and latter density filter (density filter produced) may be the same or different.
According to an 18th aspect of the present invention, there is provided a method of production of an exposure apparatus exposing by an energy beam each of a plurality of areas where peripheral parts are partially superposed on a sensitive object, comprising firing said energy beam through a density filter gradually reducing the exposure at said peripheral parts, detecting said energy beam by a photodetection device having a photodetector and light-blocking plate used for measurement of the distribution of exposure at portions corresponding to said peripheral parts on said sensitive object, and preparing a density filter formed with an attenuating part of said energy beam so that the distribution of exposure becomes a target value at said peripheral parts based on information relating to the difference between a reflectance of said light-blocking plate and a reflectance of said sensitive object, information relating to an attenuating characteristic of said density filter, and the result of said detection.
According to a 19th aspect of the present invention, there is provided a method of production of an exposure apparatus exposing by an energy beam each of a plurality of areas where peripheral parts are partially superposed on a sensitive object, comprising firing said energy beam through a density filter gradually reducing the exposure at said peripheral parts, detecting said energy beam by a photodetection device having a photodetector and light-blocking plate used for measurement of the distribution of exposure at portions corresponding to said peripheral parts on said sensitive object, and preparing a density filter formed with an attenuating part of said energy beam so that the distribution of exposure becomes a target value at said peripheral parts based on information relating to the difference between a size of said light-blocking plate and a size of an area irradiated by said energy beam, information relating to an attenuating characteristic of said density filter, and the result of said detection.
According to a 20th aspect of the present invention, there is provided a method of production of an exposure apparatus exposing by an energy beam each of a plurality of areas where peripheral parts are partially superposed on a sensitive object, comprising gradually reducing the exposure at said peripheral parts by preparing a density filter formed with an attenuating part of said energy beam so that the distribution of exposure becomes a target value at said peripheral parts based on a change in optical characteristics due to multiple exposure of said peripheral parts.
According to a 21st aspect of the present invention, there is provided an exposure apparatus exposing by an energy beam each of a plurality of areas where peripheral parts are partially superposed on a sensitive object, comprising a setting device gradually reducing the exposure at said peripheral parts, the setting device including a density filter having an attenuating part gradually reducing an energy of said energy beam, and the device changing the position of said density filter with respect to the patterns to be transferred to change the width of a second overlay part where an image of said attenuating part is superposed without changing the width of a first overlay part where said peripheral parts are superposed so as to adjust the exposure of said first overlay part.
According to a 22nd aspect of the present invention, there is provided an exposure apparatus exposing by an energy beam each of a plurality of areas where peripheral parts are partially superposed on a sensitive object, comprising a setting device gradually reducing the exposure at said peripheral parts, the setting device including a density filter having an attenuating part gradually reducing an energy of said energy beam, and the device changing the distribution of the energy beam limited by the density filter and the relative position with the patterns to be transferred so as to adjust the exposure at overlay parts where the peripheral parts are superposed.
According to a 23rd aspect of the present invention, there is provided an exposure apparatus exposing by an energy beam each of a plurality of areas where peripheral parts are partially superposed on a sensitive object, comprising a setting device gradually reducing the exposure at said peripheral parts, the setting device including a density filter having an attenuating part gradually reducing an energy of said energy beam, and the device changing the magnification of an optical system from said density filter to patterns to be transferred to change the width of a second overlay part where an image of said attenuating part is superposed without changing the width of a first overlay part where peripheral parts are superposed so as to adjust the exposure of said first overlay part.
According to a 24th aspect of the present invention, there is provided an exposure apparatus exposing by an energy beam each of a plurality of areas where peripheral parts are partially superposed on a sensitive object, comprising a setting device gradually reducing the exposure at said peripheral parts, the setting device including a density filter having an attenuating part gradually reducing an energy of said energy beam, and the device changing the optical characteristics of an optical system from said density filter to patterns to be transferred to change the distribution of the energy beam limited by said density filter and the relative position with the patterns to be transferred so as to adjust the exposure at overlay parts where the peripheral parts are superposed.